title: Stratifying risk in chronic kidney disease: an observational study of UK guidelines for measuring total proteinuria and albuminuria.
abstract: BACKGROUND
  Proteinuria predicts poor renal and cardiovascular outcomes. Some guidelines recommend measuring proteinuria using albumin:creatinine ratio (ACR), while others recommend total protein:creatinine ratio (TPCR).
  
  
  OBJECTIVE
  To compare renal outcomes and mortality in the populations identified by these different recommendations.
  
  
  METHODS
  Retrospective longitudinal cohort study.
  
  
  METHODS
  Baseline ACR and TPCR measurements were obtained from 5586 patients with chronic kidney disease (CKD) attending a Scottish hospital nephrology clinic. The cohort was divided into three groups with concordant results by ACR and TPCR (no proteinuria; low proteinuria; significant proteinuria) and one group with discordant results (significant proteinuria with TPCR, but not ACR). Outcomes were assessed using Kaplan-Meier plots and Cox proportional hazards models.
  
  
  RESULTS
  Median follow-up was 3.5 years [interquartile range (IQR) 2.1-6.0]; 844 (15%) died at 3.0 years (IQR 1.8-4.7) and 468 (8%) started renal replacement therapy (RRT) at 1.7 years (IQR 0.6-3.4). Proteinuria was associated with a substantially increased risk of RRT and death. Patients with significant proteinuria by TPCR, but not ACR (n = 231) had high renal risk, and the highest all-cause mortality (log-rank P < 0.001). With multivariate analysis the risk fell below those with significant proteinuria with concordant results by ACR and TPCR but remained considerably higher than those without significant proteinuria.
  
  
  CONCLUSIONS
  Proteinuria screening with TPCR identifies an additional 16% of patients with significant proteinuria, not identified using ACR. This subgroup has high renal risk, and high risk of all-cause mortality and therefore warrant identification. Guideline recommendations on proteinuria screening in CKD should be reconsidered.
authors.affiliation: Specialty Registrar in Nephrology and Clinical Teaching Fellow, John Stevenson Lynch Renal Unit, Crosshouse Hospital, Kilmarnock, KA2 0BE, UK. shona.methven@nhs.net
authors.forename: S
authors.initials: S
authors.lastname: Methven
authors.forename: J P
authors.initials: JP
authors.lastname: Traynor
authors.forename: M D
authors.initials: MD
authors.lastname: Hair
authors.forename: D
authors.initials: D
authors.lastname: St J O'Reilly
authors.forename: C J
authors.initials: CJ
authors.lastname: Deighan
authors.forename: M S
authors.initials: MS
authors.lastname: MacGregor
mesh_terms: D000328:Adult; D000368:Aged; D000419:Albuminuria / Q000175:diagnosis* / Q000209:etiology / Q000652:urine; D015415:Biomarkers / Q000652:urine; D015331:Cohort Studies; D003404:Creatinine / Q000652:urine*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D007676:Kidney Failure, Chronic / Q000150:complications / Q000401:mortality* / Q000628:therapy / Q000652:urine*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D017410:Practice Guidelines as Topic; D016016:Proportional Hazards Models; D011507:Proteinuria / Q000175:diagnosis* / Q000209:etiology / Q000652:urine; D017582:Renal Replacement Therapy; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D015415:Biomarkers; D003404:Creatinine